Liquid chromatography-mass spectrometry (LC-MS, or alternatively HPLC-MS) is a chemistry technique that combines the physical separation capabilities of liquid chromatography (or HPLC) with the mass analysis capabilities of mass spectrometry. LC-MS is a powerful technique used for many applications which has very high sensitivity and selectivity. Generally its application is oriented towards the general detection and potential identification of chemicals in the presence of other chemicals (in a complex mixture).
Electrospray ionization is a typical ion source that couples liquid chromatography with mass spectrometry. Electrospray ionization is also utilized in many other applications. In the electrospray ionization, liquid eluting from a chromatography column is either part of, or attached to, an emitter which has an emitter or spray tip of a diameter less than about 10 um. Electrospray formed from columns with emitters or spray tips that are fabricated by pulling glass capillaries to a few micrometers is commonly referred to as nano-electrospray or nanospray. For the production of positive ions, liquid that is forced through emitters of columns is subjected to relatively high voltage either upstream of the emitter tip or by coating the emitter (to the emitter tip and in contact with the liquid) in an electrically conductive substance. In this way, electrospray ionization induces the formation of a spray of positively charged droplets generated at the emitter tip.
As the emitter or spray tip of a chromatography and/or mass spectrometry electrospray column (e.g., a nanospray column) is a relatively delicate, expensive, small scale, highly precise and potentially hazardous component, the emitter or spray tip is typically protected by a sheath or sleeve. The protective sheath or sleeve of the column is retracted or otherwise translated away from the tip of the emitter such that at least the emitter tip is exposed during use. When not in use, however, the protective sheath or sleeve extends over the emitter tip or spray tip and an adjacent portion of the emitter to protect the emitter tip portion from damage or contamination, and to protect users from both accidental pricks and exposure to potentially hazardous materials provided in or on the emitter. In such a protective position or arrangement, the protective sheath or sleeve prevents both visual and tactile treatment of the emitter tip portion.
Treatment of the emitter tip portion may be desirable both before and after use. Specifically, it may be desirable to visually and/or tactilely treat the emitter tip portion before and after use. For example, visual inspection of the emitter tip portion may be desirable to check for damage (e.g., cracks, chips, etc.), defects, clogs or any other condition which would negatively affect the performance of the column (e.g., the spray emanating from the tip). Similarly, physical cleaning and/or inspection of the emitter tip portion may be necessary or desirable to ensure proper or adequate performance of the column.
The protective sheath or sleeve of the column makes such treatment difficult and dangerous to both the user and the emitter tip portion itself. For example, to treat an emitter tip portion before or after use of the column, a user must manually retract or otherwise move or remove the protective sheath or sleeve into a non-protective position. This is typically accomplished via one or more finger of the user, or through the use of a foreign tool or the like. Further, the user must manually maintain the retracted or non-protective position of the sheath or sleeve during treatment. Such a manual process is not only difficult, tedious and inconvenient, it is dangerous to the user and the emitter tip portion. Needle pricks, hazardous material exposure, and damage to the emitter tip portion and/or the protective sheath is likely to occur when the protective sheath is manually retracted or otherwise moved into a non-protective position, and maintained in such a position during visual and/or tactile treatment of the emitter tip portion.
As a result, a need exists for devices and methods that facilitate treatment of electrospray columns and like devices to reduce or substantially eliminate the risk of needle pricks, hazardous material exposure, and damage to the emitter tip portion and/or the protective sleeve or sheath during treatment.